---
title: "Timer"
slug: "timer-node"
updated: 2022-01-22T15:52:26Z
published: 2022-01-22T15:52:26Z
canonical: "docs.echo.stream/timer-node"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.echo.stream/llms.txt
> Use this file to discover all available pages before exploring further.

# Timer

Timer Nodes are Nodes that emit `echo.timer` message on a schedule.

Many processing tasks require executing that processing on a schedule. Some examples:

- An application drops files to process on an SFTP server, and you need to periodically query that SFTP server for new files.
- You need to call an API periodically to get the latest state and update a variety of other applications with that state.
- Every night you need to get a central database backup and update branch databases for the next day's business activities.

Timer Nodes make initiating this type of processing flow simple. To initiate such processing, simply create a Processor Node that receives `echo.timer` Nodes and execute the necessary processing when you receive one of those messages.

You may create as many Timer Nodes in your Tenant processing network as you wish.

### Schedule Expressions

When creating a Timer Node, you must provide a cron expression to specify the schedule. This cron expression must conform to the [AWS EventBridge Cron Expression](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-create-rule-schedule.html#eb-cron-expressions) format.